As a final project during my first year of college at San Jose State, I created a device that records button inputs on a Game Boy Color and allows the user to play them back at will. I used a special prototyping board provided to me by the school and wrote software for it in C.
This was an early project of mine and admittedly has very limited use. However, I learned how to work with prototyping hardware and how to solder properly. This greatly prepared me for when I started tinkering with Arduinos and building more hardware based projects.